A Combined Deblocking Filter and SAO Hardware Architecture for HEVC

Abstract

The latest video coding standard high-efficiency video coding (HEVC) provides 50% improvement in coding efficiency compared to H.264/AVC to meet the rising demands for video streaming, better video quality, and higher resolution. The deblocking filter (DF) and sample adaptive offset (SAO) play an important role in the HEVC encoder, and the SAO is newly adopted in HEVC. Due to the high throughput requirement in the video encoder, design challenges such as data dependence, external memory traffic, and on-chip memory area become even more critical. To solve these problems, we first propose an interlacing memory organization on the basis of quarter-LCU to resolve the data dependence between vertical and horizontal filtering of DF. The on-chip SRAM area is also reduced to about 25% on the basis of quarter-LCU scheme without throughput loss. We also propose a simplified bitrate estimation method of rate-distortion cost calculation to reduce the computational complexity in the mode decision of SAO. Our proposed hardware architecture of combined DF and SAO is designed for the HEVC intraencoder, and the proposed simplified bitrate estimation method of SAO can be applied to both intra- and intercoding. As a result, our design can support ultrahigh definition 7680 × 4320 at 40 f/s applications at merely 182 MHz working frequency. Total logic gate count is 103.3 K in 65 nm CMOS process.